1. Field of the Invention
The present invention relates to monitoring a state of batteries within a multi-battery power supply, and more particularly relates to a multi-battery charge/discharge circuit, multi-battery power supply, and battery-supported electronic device, which are capable of selectively testing for a physical and electrical presence of each battery wired in parallel within the circuit, supply and device, without disconnecting the battery under test from its battery discharge path (when present in-circuit).
2. Description of the Related Art
Various battery systems are known, many rechargeable. Rechargeable battery systems or power supplies have numerous uses, being found in or used with many known electronic devices and systems, particularly portable or hand-held standalones. Some devices and systems require “uninterruptible” power supplies to assure operation of a supply-supported device, if necessary, without fail. As used herein, the term battery shall be used to describe an individual battery cell, or a multiple-cell battery unit, wherein the cells are typically arranged in a serial combination to form the battery unit, or battery. The term electronic device shall be used broadly herein to include known electronic devices and systems that include battery charge/discharge circuitry for maintaining a plurality of batteries in a ready-charge state. For example, a security or fire alarm device or system is an example of an electronic device. The term alarm system, as used herein, is used to describe any known alarm-based system or device, such as a fire or smoke detection system or device, a security system, a CO or CO2 level detection system or device, etc.
Conventional battery charge/discharge circuitry includes a charge path terminal (to sink current), a discharge path terminal (to source current) and control circuitry to control battery charge/discharge operation. Such conventional circuitry, however, is unable to detect whether one of an aggregate set of batteries, fixed in place physically and maintained by the charge/discharge circuitry, is missing electrically and physically from the circuit. The legacy charge control circuitry “sees” (or electrically detects) the aggregate current source, or aggregate voltage potential at the discharge terminal, but does not “see” or readily detect, nor can verify that individual batteries are present or not present in-circuit. For that matter, conventional charge/discharge circuits require a hands-on physical removal of a battery from its receptacle to test its health, i.e., in a separate battery tester. Human error sometimes leads to a failure to replace a dead or failing battery after out-of-holder testing, or worse, we sometimes fail to re-insert a dead battery in the dead battery's holder in instances where there is no replacement battery readily available.
What is needed is a rechargeable battery circuit, multi-battery rechargeable power supply, and electronic device that includes the circuitry and/or power supply that are able to selectively test for a battery's present or missing state without disconnecting the battery from its in-circuit battery discharge path (if present), and communicating the testing result. The term “missing” as used herein is meant to describe a condition where a battery is not physically and electrically present in the circuit at its receptacle, i.e., not in-circuit.